How Much Animal Data are Required to Move into Clinical Testing? Hilary Sheevers, PhD Aclairo October 10, 2007

Transcription

1 How Much Animal Data are Required to Move into Clinical Testing? Hilary Sheevers, PhD Aclairo October 10, 2007

2 Guidances FDA is Guidance Driven Good news: guidances are on FDA s website ICH M3 for small molecules ICH S6 for large molecules In general, FDA will follow these guidances closely Regulatory climate is more conservative, so cannot simply look at past examples to understand how FDA will regulate today Exceptions: oncology and life threatening diseases for which there are only limited treatment options

3 ICH M3 small molecules Nonclinical Safety Studies for the Conduct of Human Clinical Trials for Pharmaceuticals Gives detailed description of all the animal studies needed to open an IND, and to NDA (marketing) filing Does not tell you how to interpret the studies

4 ICH M3 To open a standard IND Pharmacology (efficacy; animal proof of principle) studies A rodent general toxicology study of at least 14 days duration A non-rodent general toxicology study of at least 14 days duration Genotoxicity studies Safety pharmacology studies ADME Analytical assays

5 General toxicology studies Generally daily dosing by the same route of administration intended in the clinic Rat or Mouse? Dog or Monkey? Relevant species Metabolism similar to humans Pharmacology Species should have the pharmacological target Some species very sensitive to some drugs» Eg rats and NSAIDS, dogs and glucocorticoid steroids Practicality in terms of amount of drug available Dose levels Usually 3 dose groups and a control Want to see toxicity at highest dose Would like to see no toxicity at low does that are near the clinical dose Typical safety factor between a clean dose level (NOAEL = no observed adverse effects level) and the clinical starting dose is 10X based on mg/m 2 In addition to your 14 day studies, you generally perform a single dose IV study so you can evaluate bioavailability

6 General toxicology Observations: body weights: daily food consumption: daily cageside: 1-2 times per day plasma samples for PK analysis: last day of dosing clinical pathology: end of study, and before study start for large animals Necropsy: end Histopathology: end GLP

7 Genotoxicity tests ICH Guidance on technical issues and which tests are required Two in vitro tests to open IND Mutagenicity (Ames) Test in several bacterial strains looking for DNA damage Clastogenicity Test to evaluate chromosome damage Not expensive or time consuming Unless the result is positive!!!

8 Safety Pharmacology Additional ICH guidance on safety pharmacology testing Focus on 3 systems that if affected could result in death Single dose studies Highest dose should be somewhat toxic (maximum tolerated dose) Reason: experience has shown that findings at high doses are sometimes predictive of effects in humans following repeat doses, e.g. terfenadine

9 Safety Pharmacology Respiratory CVS Single dose rat study; some labs can incorporate this into the CVS study Single dose telemetry in dogs or monkeys Animals can be returned to the colony; can also use non-naïve animals herg (in vitro test for potassium channel activity) CNS Single dose rat study Behavioral evaluation Personal opinion: of little value

10 ADME Absorption, distribution, metabolism, and excretion Information is collected over the entire course of development At the IND filing stage, you should be starting to get an understanding on the ADME basics of your drug Analytic assay(s) is often the hardest part of getting started

11 ADME Generally get exposure data (AUC, Cmax) from general toxicology studies Rodents: add extra animals (many) Dogs or monkeys: use tox animals In vitro metabolism generally done Liver microsomes or hepatocytes Compare test species and humans Beginning to prepare for in vivo evaluations Distribution and excretion data may be collected; varies with different drugs and people

12 Analytical assays Need to quantify dose formulations for your GLP studies Needed to quantify plasma levels If complex metabolism, need over time to have an analytical assay for all major metabolites Need to quantify impurities and be sure you are below ICH levels A lot of work!

13 ICH S6 -- biologics Preclinical Safety Evaluation of Biotechnology- Derived Pharmaceuticals General toxicology Usually monkey Changing requirements on rodent No genotoxicity testing Safety phamacology needed Immunogenicity (monoclonal antibodies) Some ADME

14 Biologics challenge Regulatory oversight of biologics has changed from CBER to CDER (center for biologics to center for drugs) Small molecule M3 people are now regulating S6 S6 is fairly general Allowed CBER to not request many studies BUT now it allows CDER to request many studies

15 Other items What was described above summarize the regulatory requirements. Other things are needed to support your program outside of regulatory requirements Short, nonglp studies to identify dose levels for your GLP studies Screening assays often done to select the best candidates for GLP studies Receptor binding, Ames, herg are common screens Getting sufficient drug to perform toxicology studies often takes 9-12 months, and is the classic underestimated step

16 Example NME: Supernova drug Anti-inflammatory activity = immunomodulator First chosen indication: oral drug for psoriasis Pharmacology studies completed, support indication Would like to file IND Work out timelines 6 months needed to scale up mfg to make drug

17 Example Have small amount of drug already made for bench work Use drug to perform screening tests Ames is negative herg is positive Decision: drop lead candidate because of positive herg, or scale up and perform complete CVS evaluation? Most would drop the drug

18 Example Decide to scale up Go into non GLP dose finding studies Rats die at dose levels that, based on pharmacology, are needed for the clinical dose for efficacy Dogs are fine Decision: drop this drug, knowing that rat findings are generally about 50% effective?

19 Example You love this drug. You decide to move forward. Perform a full herg assay it is a clear positive Dog telemetry study is clean no in vivo effects Decision: stop development because of the positive herg?

20 Example You cannot believe your bad luck. The lab must have made a mistake. You know this is a great drug. You decide to go forward. You spend $500K to perform your GLP rat and dog studies The dog tolerates doses up to 1000 mg/kg See liver effects at highest dose Rat does not tolerate drug NOAEL is 1 mg/kg You will need a 10X safety factor

21 Example You are lucky! The rat toxicity is monitorable. Clinical pathology can be monitored in humans before histopathological doses FDA makes you start at a very low dose, but you are allowed to dose upward with careful monitoring Your human study demonstrates that the rat is more sensitive to the drug than humans

22 NME vs. Old drugs What is described above is for new molecular entities For already approved drugs, fewer animal studies may be needed Varies with what was done for the innovator molecule IF there are no patent issues, you have the right to use the innovator s data to support your application 505(b)2

23 Example Budesonide Glucocorticosteroid Off patent No inhaled generic steroids allowed by FDA Because cannot be quantified in PK study A full set of toxicology studies, including carcinogenicity and repro. studies done Entire tox package for new products using old ingredient is two 2-week studies and one 90 day study for the NDA

24 Example 2 Ibuproferin No patent issues Want to develop it for localized chronic pain Because no topical studies have been done, a complete dermal toxicology package, including carcinogenicity testing, would be required Message: the devil is in the details

25 Beyond the IND Your general toxicology studies must at least be equal in length (with finalized study reports) to the length of your clinical trials E.g. 14 days only supports up to 14 days in the clinic As you progress, many additional nonclinical studies are required Development is constant

26 Summary FDA is increasingly conservative, and less likely to give you a break Guidances describe needed studies They require a lot of time and money Results count! Even if you have planned and implemented the perfect program, if a drug is toxic at clinically relevant doses, the IND may never go forward PreIND meetings with the FDA are a useful place to communicate with your regulator